http://www.imore.com/sites/imore.com...?itok=eYRAIUfP
Don't worry about running out of drive space on your Mac, just learn to check it out.
Especially now that most new Macs —*especially laptops — have flash-based storage, the average amount of space on the Mac's boot volume is smaller than it has been in past years. If you're worried that you might be running out of space on your Mac, OS X makes it easy to figure out how much space you have left.